{
 "generated_utc": "2026-08-20T17:26:33Z",
 "gfs_cycle_utc": "2026-08-20T12:00:00Z",
 "model": {
  "source": "NCEP GFS 0.50 degree",
  "vertical_coordinate": "constant density (isopycnic)",
  "horizon_hours": 419.5,
  "output_interval_min": 30,
  "integration_step_s": 900,
  "wind_field_interval_h": 3
 },
 "staleness": {
  "fresh_seed_max_h": 24.0,
  "served_until_h": 336.0,
  "track_max_age_h": 72.0,
  "region_spread_deg": 60.0,
  "note": "A trajectory is served for 336 h after the last real fix and then the flight disappears. That matches the archive's own bridging limit: 23% of flights go quiet for over a week and are then heard again, so a shorter window drops balloons that are still flying. Past dead_reckoned flights the balloon has not been heard from since seed_time, so its present position is a prediction too -- the silent period is reconstructed from GFS analyses of weather that has already happened, which is why wind_source distinguishes analysis from forecast. Use display_as, not seed_age_h, to decide how to draw a flight: 'track' means the members still agree and a line is meaningful, 'region' means draw the member envelope instead because the nominal member is no better than any other."
 },
 "members": {
  "offsets_m": [
   -2000,
   -1500,
   -1000,
   -500,
   0,
   500,
   1000,
   1500,
   2000
  ],
  "nominal_offset_m": 0,
  "note": "Each member is seeded at the last observed altitude plus its offset and then conserves the density it started with. The ladder is a sensitivity fan, not a probability distribution: adjacent members diverge by roughly 1,200 km over seven days. levels_spanned reports how many GFS levels the fan actually straddles, usually 2 or 3."
 },
 "files": {
  "trajectories_csv_gz": "PBA_forecast_20260820_12Z.csv.gz",
  "trajectories_geojson_gz": "PBA_forecast_20260820_12Z.geojson.gz"
 },
 "counts": {
  "flights": 21,
  "members": 9,
  "rows": 81972
 },
 "flights": [
  {
   "callsign": "AG6NS-23",
   "flight_id": "AG6NS-23_2026-02-07",
   "payload_type": "WSPR",
   "seed_time": "2026-08-20 13:13:40",
   "seed_lat": -54.16667,
   "seed_lon": -61.99999,
   "seed_alt_m": 12300.0,
   "seed_age_h": 4.11,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-27 12:45:00",
    "lat": -83.43765,
    "lon": -115.20379,
    "alt_m": 12375.3
   },
   "member_spread_deg": {
    "lat": 37.61,
    "lon": 315.7
   },
   "member_spread_now_deg": {
    "lat": 1.0,
    "lon": 2.76
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "BSS53",
   "flight_id": "BSS53_2026-03-09",
   "payload_type": "WSPR",
   "seed_time": "2026-08-20 06:13:49",
   "seed_lat": 67.79167,
   "seed_lon": -172.20833,
   "seed_alt_m": 12390.0,
   "seed_age_h": 11.1,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-27 11:45:00",
    "lat": 76.11775,
    "lon": 2.7478,
    "alt_m": 12530.1
   },
   "member_spread_deg": {
    "lat": 32.46,
    "lon": 61.8
   },
   "member_spread_now_deg": {
    "lat": 2.46,
    "lon": 4.22
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "BSS54",
   "flight_id": "BSS54_2026-07-09",
   "payload_type": "WSPR",
   "seed_time": "2026-08-19 19:59:18",
   "seed_lat": 51.08333,
   "seed_lon": -140.58333,
   "seed_alt_m": 14060.0,
   "seed_age_h": 21.35,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-08-27 11:30:00",
    "lat": 50.94995,
    "lon": 8.70271,
    "alt_m": 13988.6
   },
   "member_spread_deg": {
    "lat": 39.61,
    "lon": 137.72
   },
   "member_spread_now_deg": {
    "lat": 7.34,
    "lon": 3.16
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DG2GG-23",
   "flight_id": "DG2GG-23_2026-05-23",
   "payload_type": "WSPR",
   "seed_time": "2026-08-20 05:49:00",
   "seed_lat": 54.375,
   "seed_lon": 147.75,
   "seed_alt_m": 12620.0,
   "seed_age_h": 11.52,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-27 11:45:00",
    "lat": 55.76659,
    "lon": -25.78951,
    "alt_m": 12430.4
   },
   "member_spread_deg": {
    "lat": 25.16,
    "lon": 46.15
   },
   "member_spread_now_deg": {
    "lat": 3.91,
    "lon": 6.65
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DG2GG-27",
   "flight_id": "DG2GG-27_2026-07-04",
   "payload_type": "WSPR",
   "seed_time": "2026-08-10 00:18:00",
   "seed_lat": 17.10417,
   "seed_lon": -113.33333,
   "seed_alt_m": 14010.0,
   "seed_age_h": 257.03,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-08-27 11:45:00",
    "lat": -1.65214,
    "lon": -37.96746,
    "alt_m": 14057.9
   },
   "member_spread_deg": {
    "lat": 49.01,
    "lon": 124.4
   },
   "member_spread_now_deg": {
    "lat": 48.15,
    "lon": 118.06
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "DG2GG-30",
   "flight_id": "DG2GG-30_2026-08-07",
   "payload_type": "WSPR",
   "seed_time": "2026-08-20 16:01:00",
   "seed_lat": 54.91667,
   "seed_lon": 15.08333,
   "seed_alt_m": 12380.0,
   "seed_age_h": 1.32,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-27 15:30:00",
    "lat": 49.41071,
    "lon": -126.73112,
    "alt_m": 12561.8
   },
   "member_spread_deg": {
    "lat": 19.42,
    "lon": 342.81
   },
   "member_spread_now_deg": {
    "lat": 0.26,
    "lon": 2.01
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DG2GG-31",
   "flight_id": "DG2GG-31_2026-08-13",
   "payload_type": "WSPR",
   "seed_time": "2026-08-20 07:22:00",
   "seed_lat": 46.85417,
   "seed_lon": 130.41667,
   "seed_alt_m": 13220.0,
   "seed_age_h": 9.97,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-27 11:45:00",
    "lat": 49.6282,
    "lon": -92.42042,
    "alt_m": 13101.3
   },
   "member_spread_deg": {
    "lat": 14.97,
    "lon": 39.57
   },
   "member_spread_now_deg": {
    "lat": 2.11,
    "lon": 8.6
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "DN3LEO-13",
   "flight_id": "DN3LEO-13_2026-04-12",
   "payload_type": "WSPR",
   "seed_time": "2026-08-20 10:08:00",
   "seed_lat": 78.95833,
   "seed_lon": 117.79167,
   "seed_alt_m": 11880.0,
   "seed_age_h": 7.2,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-27 11:45:00",
    "lat": 80.40046,
    "lon": 22.97042,
    "alt_m": 12005.5
   },
   "member_spread_deg": {
    "lat": 31.74,
    "lon": 284.6
   },
   "member_spread_now_deg": {
    "lat": 1.91,
    "lon": 3.17
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "EI6BFW-18",
   "flight_id": "EI6BFW-18_2026-07-25",
   "payload_type": "WSPR",
   "seed_time": "2026-08-20 16:48:00",
   "seed_lat": 58.39583,
   "seed_lon": -17.91667,
   "seed_alt_m": 12670.0,
   "seed_age_h": 0.53,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-27 16:15:00",
    "lat": 66.22727,
    "lon": 69.11626,
    "alt_m": 12367.1
   },
   "member_spread_deg": {
    "lat": 9.89,
    "lon": 59.31
   },
   "member_spread_now_deg": {
    "lat": 0.18,
    "lon": 0.12
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "K5NOT-11",
   "flight_id": "K5NOT-11_2026-06-20",
   "payload_type": "WSPR",
   "seed_time": "2026-08-15 20:50:37",
   "seed_lat": 40.97911,
   "seed_lon": -75.41666,
   "seed_alt_m": 13300.0,
   "seed_age_h": 116.49,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-27 11:45:00",
    "lat": 28.82872,
    "lon": -106.59652,
    "alt_m": 13384.2
   },
   "member_spread_deg": {
    "lat": 45.61,
    "lon": 181.12
   },
   "member_spread_now_deg": {
    "lat": 27.4,
    "lon": 46.49
   },
   "display_as": "region",
   "display_reason": "seed_age"
  },
  {
   "callsign": "KC3LBR-449",
   "flight_id": "KC3LBR-449_2026-07-06",
   "payload_type": "WSPR",
   "seed_time": "2026-08-20 15:04:33",
   "seed_lat": 73.9375,
   "seed_lon": 98.875,
   "seed_alt_m": 13190.0,
   "seed_age_h": 2.26,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-27 14:30:00",
    "lat": 63.55179,
    "lon": -150.97089,
    "alt_m": 13116.0
   },
   "member_spread_deg": {
    "lat": 29.89,
    "lon": 302.64
   },
   "member_spread_now_deg": {
    "lat": 0.25,
    "lon": 0.74
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KC5TRB-1",
   "flight_id": "KC5TRB-1_2026-06-20",
   "payload_type": "WSPR",
   "seed_time": "2026-08-12 11:40:43",
   "seed_lat": 57.39578,
   "seed_lon": 26.00003,
   "seed_alt_m": 12570.0,
   "seed_age_h": 197.66,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-27 11:45:00",
    "lat": 57.08196,
    "lon": 91.08252,
    "alt_m": 12589.8
   },
   "member_spread_deg": {
    "lat": 40.36,
    "lon": 289.87
   },
   "member_spread_now_deg": {
    "lat": 29.0,
    "lon": 300.05
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "KD7FXO-1",
   "flight_id": "KD7FXO-1_2026-08-02",
   "payload_type": "WSPR",
   "seed_time": "2026-08-20 05:57:30",
   "seed_lat": 47.08333,
   "seed_lon": 167.5,
   "seed_alt_m": 13130.0,
   "seed_age_h": 11.38,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-27 11:30:00",
    "lat": 32.88167,
    "lon": -173.90744,
    "alt_m": 13163.6
   },
   "member_spread_deg": {
    "lat": 11.49,
    "lon": 106.88
   },
   "member_spread_now_deg": {
    "lat": 3.73,
    "lon": 5.06
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KE8RES-8",
   "flight_id": "KE8RES-8_2026-06-20",
   "payload_type": "WSPR",
   "seed_time": "2026-08-20 10:01:00",
   "seed_lat": 85.25,
   "seed_lon": 45.875,
   "seed_alt_m": 11960.0,
   "seed_age_h": 7.32,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-27 11:30:00",
    "lat": 65.77923,
    "lon": 153.79915,
    "alt_m": 12097.3
   },
   "member_spread_deg": {
    "lat": 20.05,
    "lon": 265.78
   },
   "member_spread_now_deg": {
    "lat": 1.71,
    "lon": 32.74
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "KE9DAB-11",
   "flight_id": "KE9DAB-11_2026-07-29",
   "payload_type": "WSPR",
   "seed_time": "2026-08-13 21:11:00",
   "seed_lat": 63.66667,
   "seed_lon": 161.54167,
   "seed_alt_m": 10970.0,
   "seed_age_h": 164.15,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-27 11:45:00",
    "lat": 29.50574,
    "lon": -9.69805,
    "alt_m": 11255.8
   },
   "member_spread_deg": {
    "lat": 41.04,
    "lon": 215.57
   },
   "member_spread_now_deg": {
    "lat": 17.55,
    "lon": 103.76
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "KI6DS-11",
   "flight_id": "KI6DS-11_2026-02-03",
   "payload_type": "WSPR",
   "seed_time": "2026-08-20 07:15:45",
   "seed_lat": 67.12495,
   "seed_lon": 152.95835,
   "seed_alt_m": 12930.0,
   "seed_age_h": 10.07,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-27 11:45:00",
    "lat": 75.34418,
    "lon": 14.2516,
    "alt_m": 13122.0
   },
   "member_spread_deg": {
    "lat": 5.81,
    "lon": 183.92
   },
   "member_spread_now_deg": {
    "lat": 0.43,
    "lon": 2.4
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "SP2ROC-41",
   "flight_id": "SP2ROC-41_2026-01-25",
   "payload_type": "WSPR",
   "seed_time": "2026-08-20 11:01:00",
   "seed_lat": 8.70833,
   "seed_lon": 71.20833,
   "seed_alt_m": 16270.0,
   "seed_age_h": 6.32,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-08-27 11:30:00",
    "lat": 1.35929,
    "lon": -4.48485,
    "alt_m": 16431.4
   },
   "member_spread_deg": {
    "lat": 24.45,
    "lon": 60.15
   },
   "member_spread_now_deg": {
    "lat": 0.92,
    "lon": 4.65
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "VE3VRO-36",
   "flight_id": "VE3VRO-36_2026-07-30",
   "payload_type": "WSPR",
   "seed_time": "2026-08-20 16:36:00",
   "seed_lat": 31.41667,
   "seed_lon": -135.04167,
   "seed_alt_m": 13360.0,
   "seed_age_h": 0.73,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-27 16:00:00",
    "lat": 35.73814,
    "lon": 18.41464,
    "alt_m": 13500.5
   },
   "member_spread_deg": {
    "lat": 26.01,
    "lon": 78.75
   },
   "member_spread_now_deg": {
    "lat": 0.14,
    "lon": 0.24
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "W0RBO-12",
   "flight_id": "W0RBO-12_2026-05-02",
   "payload_type": "WSPR",
   "seed_time": "2026-08-20 16:55:23",
   "seed_lat": 64.10411,
   "seed_lon": -105.33331,
   "seed_alt_m": 12900.0,
   "seed_age_h": 0.41,
   "float_reliable": true,
   "dead_reckoned": false,
   "levels_spanned": 2,
   "nominal_end": {
    "valid_time": "2026-08-27 17:00:00",
    "lat": 58.95042,
    "lon": -51.9591,
    "alt_m": 12989.8
   },
   "member_spread_deg": {
    "lat": 21.21,
    "lon": 86.68
   },
   "member_spread_now_deg": {
    "lat": 0.05,
    "lon": 0.12
   },
   "display_as": "track",
   "display_reason": "fresh"
  },
  {
   "callsign": "ZS6SRC-37",
   "flight_id": "ZS6SRC-37_2026-07-31",
   "payload_type": "WSPR",
   "seed_time": "2026-08-17 20:59:00",
   "seed_lat": -20.58333,
   "seed_lon": -72.33333,
   "seed_alt_m": 12210.0,
   "seed_age_h": 68.35,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 3,
   "nominal_end": {
    "valid_time": "2026-08-27 11:30:00",
    "lat": -30.77287,
    "lon": 84.08606,
    "alt_m": 12355.5
   },
   "member_spread_deg": {
    "lat": 32.11,
    "lon": 280.76
   },
   "member_spread_now_deg": {
    "lat": 23.35,
    "lon": 107.21
   },
   "display_as": "region",
   "display_reason": "member_spread"
  },
  {
   "callsign": "ZS6SRC-39",
   "flight_id": "ZS6SRC-39_2026-08-05",
   "payload_type": "WSPR",
   "seed_time": "2026-08-12 06:21:00",
   "seed_lat": -22.16667,
   "seed_lon": 146.45833,
   "seed_alt_m": 15900.0,
   "seed_age_h": 202.98,
   "float_reliable": true,
   "dead_reckoned": true,
   "levels_spanned": 1,
   "nominal_end": {
    "valid_time": "2026-08-27 11:45:00",
    "lat": -34.64074,
    "lon": 109.61982,
    "alt_m": 15328.6
   },
   "member_spread_deg": {
    "lat": 27.46,
    "lon": 280.28
   },
   "member_spread_now_deg": {
    "lat": 23.43,
    "lon": 166.55
   },
   "display_as": "region",
   "display_reason": "member_spread"
  }
 ]
}